The Advantage Database Client ServerDesktop database applications developed with tools such as CA-Clipper, FoxPro, Visual Basic and Delphi have traditionally been popular because they are relatively inexpensive to implement and deploy. But as more users and Internet and remote access capabilities are added, performance, data integrity and security begin to suffer. Moving the application to a client/server platform is the perfect solution. When a PC database application is used by only a few users on a LAN, and the database is small, the application usually provides good performance, is easy to maintain, and is relatively stable. Very small user sites often acquire additional tools for use against their database, such as report generators and database browsers. Everything is running smoothly and all database tools are in place. Performance is good and the database is stable. Increasing Users Increases the ProblemsAs the number of application users at the site increases, the size of the database doubles, then triples. Transaction loads skyrocket. A remote site is added that requires access to the home site data via a WAN. Suddenly, performance has slowed to a crawl. The network is swamped with traffic and index corruption becomes commonplace. When workstations or the network go down, the database becomes corrupt. With the addition of new users, there is now a need to limit access to key data. Database security becomes a larger issue. Performance is declining. Accessing the database on the LAN is taking longer, and performance of the WAN is even worse—it is unusable. The database is no longer stable or secure. Users have lost their ability to do their work in a timely manner. Why the Performance DeclinedWith desktop database applications, the user interface, business calculations, database concurrency control, data movement, data searching, and data manipulation are all performed on the workstation. The file server only acts as a shared hard drive. There is no central point of control to the data. When a workstation needs to search for, read, write, or otherwise access data, it must first attempt to provide database concurrency by locking the data it needs to access. With only a few users on the system, there is little contention for common data. However, as the number of users at a site increases, so does database access contention. The workstation data locking attempts will fail more frequently on initial and subsequent attempts. Not only does the individual application performance suffer but other users’ application performance suffers due to the additional network traffic generated by multiple database concurrency lock requests. The performance problems have become a double-edged sword. The database concurrency locking requires multiple retries and the additional network traffic makes it tougher to make the lock requests. Why There is More Frequent Index CorruptionThe increased frequency of index corruption also has a simple explanation. Every time a table record is to be updated, one or more index files usually also require changes to complete the update operation. Once an update operation begins, the database will only remain in a stable state if each and every table and index update is completed. Each individual index update operation requires a concurrency lock to be obtained, index page(s) to be read and written, the index header to be read and written, and finally an index “flush to disk” operation to occur. This is for each and every index affected! If the workstation or network goes down at any time during the update operation, indexes will be corrupt and the database will be left in an unstable state. Advantage Database Server Brings You the Benefits of Client/ServerA move to client/server is in order. What is needed is a product that provides all the security and integrity benefits of client/server and all the performance benefits that should be available in a client/server environment—while allowing developers to keep all their existing applications, their existing hardware, and their years of accumulated expertise. The product that delivers is Advantage Database Server.
Use What You Already Have, Add to What You Already KnowThe Advantage Database Server brings client/server functionality to existing database applications. No application re-write is necessary. Advantage provides plug-and-play client interfaces for the most popular development platforms, including Delphi, C++Builder, Kylix, Visual Basic, Access, Perl, PHP, CA-Clipper and CA-Visual Objects. Since you do not have to change applications or tools, and no user training is necessary, existing system expertise can continue to be used. The Advantage Database Server does not require new dedicated server hardware. It runs on existing NetWare, Windows NT/2000, Linux, or Windows 95/98/ME servers. Advantage Database Server installs in minutes and is easy to maintain. It does not require a database administrator for maintenance like other database systems. Advantage also allows developers to convert their existing applications one at a time to use the Advantage Database Server, eliminating lengthy down time during integration. If your site has multi-user performance problems, suffers from data corruption, and lacks database security, it is time to look for a client/server solution. Advantage Database Server is simply the best client/server solution available. Advantage provides the performance, database integrity, and database security expected in client/server systems without requiring application re-write, new hardware or loss of existing expertise. This document is copyright by Extended Systems and is reprinted by permission. All trademarks and registered trademarks are the properties of their respective companies. Information subject to change without notice. ADV-0739–0103 Extended Systems provides the expertise, strategy and solutions to help enterprise organizations realize their business goals through mobile technology. The company’s software and services portfolio includes mobile data management solutions; mobile applications for sales, service and pharmaceutical professionals; mobile application development tools and services; client/server database management system; and Bluetooth and IrDA wireless connectivity software.
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